The present invention relates in general to wet cooling towers or to wet/dry cooling towers and in particular to a device for transferring cooling water of such towers after its heat exchange with cooling air in a recirculating means which returns cool water to a distributing installation at the top of the tower. Wet cooling towers or wet sections of wet/dry cooling towers are conventionally designed in such a manner that cooling water after discharge from heat exchanging elements for example of built-in scrubbing units, freely flows by the force of gravity into an underlying collecting basin from which it is pumped up back in the water distributing device. In this arrangement the space below the heat exchanging elements, the so-called rain zone through which cooling air streams upwards to the cooling elements, causes about 20 to 40% of the total pressure loss. On the other hand, in the rainy zone only 10% maximum of the total heat transfer takes place. In addition, because of the height of fall of the cool water which corresponds approximately to the height of the cooling air stream, the requisite pumping installations consume approximately 0.5% of the total electrical output of the power station.
On the basis of this knowledge, attempts have been already made to reduce the dimension of the height of the cooling air stream so as to reduce operational costs which are affected by the size of the stream of cooling air. This measure however has the disadvantage that the reduced height of the air inflow causes a non-uniform throughflow in the cooling tower and, to achieve the efficiency attainable at a larger air stream height the tower must have been constructed substantially higher.
The problems encountered in designs using different heights of the cooling air stream (increased height of the air stream causes higher operational costs, while lower height of the air stream causes higher investment costs due to increased height of the tower) can be avoided if a solution is found how to fetch and collect the cool water immediately below the heat exchanging elements. In this case, independently from the geodetical level of installation of the heat exchanging elements, the requisite efficiency of the transfer would be practically always of the same magnitude namely of that corresponding to the least imaginable pressure head.
A prior art suggestion in this direction is known from the Cerman publication DE-OS No. 26 19 407. In this design, there are employed water guiding plates of a wave shaped vertical cross-section acting as scrubber plates and being provided in the range of their lower edge with water collecting channels extending in longitudinal direction of the plates whereby the channels can be arranged unilaterally or at both sides of the plates or superposed vertically one above the other. Since all cooling water drizzles down on the water guiding plates and is caught in collecting channels, free cross-sectional area available for the stream of cooling air flowing up from below between the water collecting channels is limited to a size which amounts maximum to about one quarter to one half of the total used for cross-sectional area of the tower. This limitation is generally independent on the shape of the water guiding plates and of the water collecting channels. Due to the fact that the water collecting channels drastically constrict the cross-section for the throughflow of the cooling air, the effective share of the throughflow cross-section is substantially below 15%. This reduced inflow cross-section in turn causes additional pressure losses which would require larger cooling towers and increased investment costs.